Mixture-Substances powerpoint presentation

A powerpoint presentation about substances and mixtures.

1. Grade 7 Science
Mixtures &
Pure
Substances

2. MATTER
Heterogeneous
mixture
Is it uniform
throughout?
No
Homogeneous
Yes
Can it be separated
by physical means?
Pure Substance Homogeneous
Mixture (solution)
Can it be decomposed
into other substance by
a chemical process?
Element
Compound
No yes
No yes

3. Mixed or Pure?
Suppose you pick up a rock on the
beach. You see there are some parts of
it that are grey, white, blue. You
conclude that the different-coloured
parts of the rock must be different types
of matter. Is this a reasonable
conclusion?

4. Mixed or Pure?
With a partner, select two of the
following pairs of items and list as many
differences as you can:
Vinegar and water
Aluminum foil and plastic wrap
Steel and glass
Molasses and cooking oil
Metal paper clips and saw dust

5. Mixtures vs. Pure
Substances
Mixtures...
MAY have distinct visible
components.
MAY appear uniform
throughout.

6. They are the physical combination
of two or more pure substances.
+
Sugar Water
=?

7. Examples of Mixtures…
•salt water, kool-aid
•chocolate chip cookie
•muddy water
•salad dressing

8. Examples of Mixtures…
•Air

9. Pure Substances...
ALWAYS appear as
uniform throughout
They contain either a single
atom or two or more atoms
chemically combined to
form a different substance.

10. Limestone- A Pure Substance
(Calcium Carbonate)
Limestone is a sedimentary rock
composed of calcium carbonate
(CaCO
3).
Has many uses: including as building
material, filler in products such as
toothpaste or paints.

11. Water- A Pure Substance
Water is a chemical substance with the
chemical formula H
2O. A water
molecule contains one oxygen and two
hydrogen atoms connected by covalent
bonds.

12. Examples of Pure
Substances
•sugar (C
12
H
22
O
11
)
•gold (Au), copper (Cu)
•carbon dioxide (CO
2
)
•oxygen (O
2)

13. USING THE PARTICLE THEORY OF MATTER WE
CAN DISTINGUISH BETWEEN A PURE
SUBSTANCE AND A MIXTURE
Pure Substance: has only ONE type of particle
Example: gold, iron
Mixture: has 2 or more types of substance in it. We can also
say it has 2 or more types of particles mixed together
Example: sweetened water
A Quick Review of chapter so far:

14. Pure Substances:

15. •Pure Substances ALWAYS appear as uniform (the
same) throughout
Pure Substances:

16. Mixtures are the combination of two or more types of
substances.
Sugar – Water- Mixture
pure substance pure substance
Mixtures:

17. The Particle Theory Can help
explain the difference between
pure substances and mixtures:

18. Homogeneous &
Heterogeneous
Mixtures

19. Homogeneous Mixture
also called
solutions
can be solid,
liquid or gas
Stainless steel

20. the particles
are evenly
mixed so that
none of the
original
substances
are visible
Kool-aid

21. they appear
to be ONE
substance
light passes
through
unaffected

22. Heterogeneous Mixtures
also called
mechanical
mixtures
can be solid,
liquid or gas
Granola bar

23. the different
parts are visible
to the eye (may
need a
microscope)
the particles do
not evenly mixConcrete

24. Light will
reflect
perpendicular
to the
direction of
the beam

25. The Tyndall Effect
A phenomenon that can be
used to distinguish between
solutions and what appears to
be a solution
cannot be used to distinguish
between a solution and a
pure liquid

26. In a Solution...
Light passes
unaffected (if a student
looks at the beaker
perpendicular to the
direction of the beam
they will NOT see it

27. In a Mechanical Mixture...
The light will scatter
as it passes through
the mixture because
all particles are not
dissolved (as shown
on the left)